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Your race team was likely comparing a light set of 18's to a light set of 19's.

The BMW 18's that came on my car were nearly 27lbs. The "semi" forged wheels I bought are 22lbs(rears are more like 24lbs. I could have spent more and bought 18-20lb 19" wheels. Then factor in further weights savings by careful tire selection. The weight savings may be enough to counteract the sidewall attributes you brought up.

We may be getting to the point of splitting hairs where trial and error would have to reveal which would work better.

A rim size comparison is only going to be valid if we are comparing the same model rim and the same model tires in different sizes but I agree it would have to be trial and error with the tests made on the same car, with the same driver and under the same conditions to be conclusive.

A rim size comparison is only going to be valid if we are comparing the same model rim and the same model tires in different sizes but I agree it would have to be trial and error with the tests made on the same car, with the same driver and under the same conditions to be conclusive.

CA

I brought up equipping the 335 tested with the M-Performance wheel. Granted I hate it's looks and I think 20's are silly on a 3 series, BUT, the stock 18's are about 27lbs and the 20's being a Forged 1pc wheel, lets guess they are 22lbs. That is a near 20% reduction per corner before factoring in tires. This was all traced back to equipping the 335 properly for this test which BMW dropped the ball doing.

I brought up equipping the 335 tested with the M-Performance wheel. Granted I hate it's looks and I think 20's are silly on a 3 series, BUT, the stock 18's are about 27lbs and the 20's being a Forged 1pc wheel, lets guess they are 22lbs. That is a near 20% reduction per corner before factoring in tires. This was all traced back to equipping the 335 properly for this test which BMW dropped the ball doing.

BJ is mostly right on this (yes, I know, don't feed the bears). BMW's 3 series has grown...like all of the competitors have grown...because the MAJORITY of their CUSTOMERS want it. Combine that with everybody's desire for more tech (heck, there are more "bluetooth / phone" posts on "enthusiast" forums than there are power adder posts these days), smoother rides, government CAFE and EPA requirements and well...you get the current 3 series.

What is interesting to me is that this has more or less always been the case, yet those tiny, sub-compact, and harsh riding cars have sold very well. That's because the badge is almighty.

I have to note though that the old BMWs (E36 and E39) I have driven or sat in as a passenger always felt firm but very supple and smooth. I have never been inside an E90 while moving, so I don't know what people are describing as harsh. Is the the sport suspension, the older RFTs, or a combination? I assume the latter.

What is interesting to me is that this has more or less always been the case, yet those tiny, sub-compact, and harsh riding cars have sold very well. That's because the badge is almighty.

I have to note though that the old BMWs (E36 and E39) I have driven or sat in as a passenger always felt firm but very supple and smooth. I have never been inside an E90 while moving, so I don't know what people are describing as harsh. Is the the sport suspension, the older RFTs, or a combination? I assume the latter.

Suspension technology has come a long way in the last few years so while harsh riding cars may have been an acceptable trade off a few years ago that is no longer the case.

IMO the "harshness" of the E9x (at least with the sport suspension) was a combination of the RFTs and poorly calibrated shocks. As I have posted here before replacing the RFTs and installing Koni FSD shocks solved the problem. The car still has a firm ride (which is fine with me) but it is no longer harsh, does not crash over road imperfections and I have not experienced a "Pothole Explosion" since I made the modifications. If the car has left the factory in the state it is in now I would have had no complaints about the suspension.

When I bought new tires for the E93 last summer (I bought Conti DWS) I was very tempted to go with the latest generation RFTs but I had been burned so badly by the crap Bridgestones that came on the car I decided against it.

The 750 has RFTs and I have no issues with them on that car but the setup on my 2007 335i was definitely not ready for prime time.

The weight savings may be enough to counteract the sidewall attributes you brought up.

When it comes to larger wheels, the penalty is not simply the extra weight, but also the increased moment of inertia (AKA rotational inertia). Even with identical weight, the 19" will have higher moment of inertia than 18", which will affect acceleration. Moment of inertia for a small mass m scales with m * r^2, where r is the radius about the axis of rotation. Note how it is a squared term. The big heavy rim of the wheel will be one inch further out from the axle, increasing moment of inertia by about 11% (for the rim alone). I would have to make a back of the envelope calculation to know to what extent this affects acceleration, but in the hair splitting regime it may make a very real difference.

Suspension technology has come a long way in the last few years so while harsh riding cars may have been an acceptable trade off a few years ago that is no longer the case.

But how about the older cars like the E36? My point is that they weren't harsh, even with sport pack. Perhaps the standard for sportiness were lower back then? Or the tires were higher profile and obviously not RFT?

But how about the older cars like the E36? My point is that they weren't harsh, even with sport pack. Perhaps the standard for sportiness were lower back then? Or the tires were higher profile and obviously not RFT?

I think BMW had a major issue with harshness on the E9x sport suspension and I am not the only one who felt that way,

What is interesting to me is that this has more or less always been the case, yet those tiny, sub-compact, and harsh riding cars have sold very well. That's because the badge is almighty.

I have to note though that the old BMWs (E36 and E39) I have driven or sat in as a passenger always felt firm but very supple and smooth. I have never been inside an E90 while moving, so I don't know what people are describing as harsh. Is the the sport suspension, the older RFTs, or a combination? I assume the latter.

I disagree....at least partially. How many times have we all read someone new come to Bimmerfest and say something like this, "I had never driven a BMW and had no interest. Thought BMW was all hype and BMW drivers are jerks. OMG I can't believe how great this car drives! I've never driven anything like it! I love my new car! I can't stop driving. I'm constantly looking for an excuse to drive. Now I understand about BMWs!"? The brand may be powerful, but there's a reason for that. I never have come across a group of car owners as effusive as BMW owners.

The BMW CCA is the largest car club in the country, over 75,000 members according to the all knowing Wikipedia.. It's at least twice, and I think close to three times, as big as the Porsche club.

Regarding the E90 ride, I agree it is probably the latter. I do not share that opinion. I've driven my '06 E90 sport package 330i all over north Texas and now all around Chicagoland and I rarely experience unpleasant suspension issues.

When it comes to larger wheels, the penalty is not simply the extra weight, but also the increased moment of inertia (AKA rotational inertia). Even with identical weight, the 19" will have higher moment of inertia than 18", which will affect acceleration. Moment of inertia for a small mass m scales with m * r^2, where r is the radius about the axis of rotation. Note how it is a squared term. The big heavy rim of the wheel will be one inch further out from the axle, increasing moment of inertia by about 11% (for the rim alone). I would have to make a back of the envelope calculation to know to what extent this affects acceleration, but in the hair splitting regime it may make a very real difference.

True...

But I have never put a larger wheel on a car without the wheels being lighter than the oem setup.

Plenty of people go only by looks and throw on 30lb wheels and alter the braking, handling and acceleration. Not my MO.

I disagree....at least partially. How many times have we all read someone new come to Bimmerfest and say something like this, "I had never driven a BMW and had no interest. Thought BMW was all hype and BMW drivers are jerks. OMG I can't believe how great this car drives! I've never driven anything like it! I love my new car! I can't stop driving. I'm constantly looking for an excuse to drive. Now I understand about BMWs!"? The brand may be powerful, but there's a reason for that. I never have come across a group of car owners as effusive as BMW owners.

The BMW CCA is the largest car club in the country. It's at least twice, and I think close to three times, as big as the Porsche club.

Regarding the E90 ride, I agree it is probably the latter. I do not share that opinion. I've driven my '06 E90 sport package 330i all over north Texas and now all around Chicagoland and I rarely experience unpleasant suspension issues.

I agree. BMW has a very loyal following primarily based on the way the cars drive, because lets face it as a luxury car the 3 does not really offer any luxury features that are not readily available on many other brands. The driving dynamics is what traditionally has set BMW apart from the competition.

The way the cars drive is what built the brand and what made me determined to solve the "Pothole Explosions" issue since there was so much about the driving dynamics that I liked. In spite of my displeasure with the E9x suspension I resolved it and I did buy a second BMW (although not another 3er) which I have no issues with,

Obviously BMW needs to evolve with technology and with the market but if they lose sight of what built the brand they will very likely start losing market share.

But how about the older cars like the E36? My point is that they weren't harsh, even with sport pack. Perhaps the standard for sportiness were lower back then? Or the tires were higher profile and obviously not RFT?

Bingo! 15", 16", even 14" wheels were the norm. Back then 16" wheels were getting big and 17" wheels were just massive.

And, as you yourself have kept us abreast from your conversations with BMW executive types, they remain keenly aware of what got them where they are today.

When I look at BMW's "i" car development and their carbon fiber development it gives me confidence that BMW is forward looking enough that their success will continue.

I think BMW learned a lot from Lexus (what is debatable is whether Lexus learned anything from Lexus). In the 1970s Toyota (Lexus) was looking very far into the future and was planning on bringing a car to market that would be in place when their loyal customers were ready to move upmarket. What they did not do is loose sight of what made their customers loyal which was value and reliability. When the Lexus brand was introduced they were in the right place at the right time. The average age of Cadillac (the best selling luxury brand at the time) was increasing every year and Lexus had a youthful image. Now Lexus is in the same position as the average age of a Lexus customer is increasing every year. Lexus is also very aware of the fact that their cars are viewed as being bland and not particularly involving to drive. They are aware that this is hurting them and that is why they came out with the LF-A, which was an image car that they probably lost money on.

The problem with selling to the "Status Symbol" crowd is that they tend to be very unlnowlegable, fickle, are primarily buying purely for the badge. As their perception changes they will leave the brand. This may take a while as there were still loyal Cadillac buyers who were convinced that they were buying high quality status symbols when Cadillac was selling anachronistic, unreliable junk.

A number of years ago I spoke to someone from Timberline (the shoe company) whose products had become a huge fad among yuppies and urban youth. He explained that although they certainly appreciated the spike in business Timberline was not going to go to any great expense to market to what they viewed as a very transient market that could disappear as fast as it has appeared. They continued to cater to their long term clientele and this proved to be a very smart move.

Today Cadillac is fighting to regain the position at the top of the luxury car market that they contolled at one time. Cadillac has done this before although this was a long time ago. In the late 1920s Cadillac was in the position of being viewed as a staid, old man's car. GM President Alfred Sloan and legendary designer Harley Earl introduced the LaSalle (in case anyone was wondering what Archie and Edith were singing about when they said "Gee our old LaSalle ran great") which was in a sense the first Yuppie car (long before the term Yuppie was coined). The LaSalle was a sporty more youthful oriented Cadillac. The LaSalle brand did not survive World War II but it had a large influence on post war Cadillacs which dominated the post war luxury car market and sat at the top of the GM brand hierarchy of Chevrolet, Pontiac, Oldsmobile, Buick and Cadillac. In those days the 5 GM brands were very different and shared few components. For instance each brand had unique V8 engines. The post war Cadillacs were viewed as high performance luxury cars and the name Cadillac was synonymous with quality, luxury and prestige.

Perhaps Cadillac should have done the same thing again and branded the CTS and the ATS as LaSalles instead of Cadillac. It probably occurred to them and the idea was rejected.

Now BMW is in a sense at a crossroads. As they gain market share they need to build cars that appeal to a wider audience without losing appeal to the customer base that built the brand. Whether they succeed or not (and I suspect they will) will not be obvious for several years but as history has shown when you are at the top the only place you can go is down. Audi and the Japanese brands are nipping at their heels, Mercedes is a very solid brand and the Koreans are rapidly moving upscale. Lexus in particular is very interested in developing a more sporty image and they have the engineering expertise to do so. Lexus beat BMW and Mercedes at their own game in the past (Lexus was the best selling luxury brand for years) and there is no reason to believe it can't happen again. If the posters here don't think it is a possibility I am sure that BMW is watching those brands very closely. BMW may have made a misstep or two along the way but they are are very well run company with very good resources and I am sure they are looking at the big picture and very far into the future. If the word on the street is that other brands are beating BMW at their own game I would expect that they will take immediate action to rectify the situation. They may or may not have reached their peak but I suspect they will remain a major player for a long time.

I can assure you that nobody at BMW is taking the attitude "BMW is no longer an enthusiast car" and I suspect that anyone who does will find him(her)self unemployed.

In college I took a senior level history course called The Automobile in American History. Loved that course. Reviving the LaSalle name wouldn't have worked for Cadillac/GM. It may have had a positive effect on post-war Cadillac products, but the name became equated with a brand failure. That would be bad for those who made the connection and on the flipside would be those for whom the name had no meaning due to no brand recognition. Reminds me of Ford's attempt to revive the name 500. It had meaning for them, but no more public brand recognition. They, of course, quickly renamed it the Taurus.

The problem with this latest attempt from Lexus is that they've created more of a "boy racer", "Japanese ricer" look to those cars.

I mentioned this in another post - BMW is suffering some now from their own innovation and success. Driving performance, handling, and dynamics technology is reaching its limit and now economies of scale are allowing everyone and their grandmother to have what used to be high-end technology. And then electronic/computer technology is so prolific everyone can have it and it's hard to keep up with all the advancements.

In college I took a senior level history course called The Automobile in American History. Loved that course. Reviving the LaSalle name wouldn't have worked for Cadillac/GM. It may have had a positive effect on post-war Cadillac products, but the name became equated with a brand failure. That would be bad for those who made the connection and on the flipside would be those for whom the name had no meaning due to no brand recognition. Reminds me of Ford's attempt to revive the name 500. It had meaning for them, but no more public brand recognition. They, of course, quickly renamed it the Taurus.

The problem with this latest attempt from Lexus is that they've created more of a "boy racer", "Japanese ricer" look to those cars.

I mentioned this in another post - BMW is suffering some now from their own innovation and success. Driving performance, handling, and dynamics technology is reaching its limit and now economies of scale are allowing everyone and their grandmother to have what used to ne high-end technology. And then electronic/computer technology is so prolific everyone can have it and it's hard to keep up with all the advancements.

The there's all the changing propulsion system possibilities.

It's a brave, new automotive world automakers are facing.

It probably would not have been a good idea for Cadillac to revive the LaSalle name and you are correct it has virtually zero brand recognition in today's market since the brand was discontinued in 1940. One of the reasons that GM dropped it was because the cars had grown in size and were competing with the Cadillac brand.

I'm just perplexed why BMW doesn't just put Michelin PS2 RFTs and just call it a day in all the 3 series. It's what they used to do in the non-RFT days. None of this silly AS or summer tire combinations. PS2s or PSS are just as good in dry or wet weather with reasonable tread life; excluding snow of course. Hopefully an RFT for the PSS comes out soon as the treadware is much better than the PS2s.

Conspiracy theorist in me (when I wear tin-foil hat) says they didn't want to force customers to (almost) mandatory tire change and expose them to non-run flats. I know, I accepted my car's shenanigans (steering wheel tug, vibrations of cabin panels, noise, truck driving experience) faulting myself for wanting ZSP equipped car UNTIL I had to switch to winter tires. Then I knew it wasn't my fault. I also know right now it wasn't my fault because on Michelin PSS go-flat tires the car is superb.

I'm still strongly convinced that, if 100% of E9x and F30 owners were forced to switch to go-flat rubber, less than 10% would go back to RFT - regardless of all "safety" and "convenience" arguments you can read on these boards.

" It just seems the target market for this latest generation is more towards the main stream of drivers which drives the most volume of revenue and sales. Can't blame BMW, it's what makes Toyota and Honda lots of money. So they have achieved to get into the mainstream market while appeasing their enthusiast followers; even if it requires more customization than previously needed from their older generation 3 series."[/QUOTE]

When it comes to larger wheels, the penalty is not simply the extra weight, but also the increased moment of inertia (AKA rotational inertia). Even with identical weight, the 19" will have higher moment of inertia than 18", which will affect acceleration. Moment of inertia for a small mass m scales with m * r^2, where r is the radius about the axis of rotation. Note how it is a squared term. The big heavy rim of the wheel will be one inch further out from the axle, increasing moment of inertia by about 11% (for the rim alone). I would have to make a back of the envelope calculation to know to what extent this affects acceleration, but in the hair splitting regime it may make a very real difference.

A 3500 lb car would have 1/2 (3500 lb) V^2 kinetic energy, while the KE of four 40 lb wheel/tires would be 2 (40lb) V^2. Add 11% and it would be 2 (44 lb) V^2.

8 /1750 lbs = 0.5%. Like losing 1 hp. Not anything you would notice.

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